This invention relates to a tape reel, and particularly to a reel for storing magnetic tape such as is used with computers.
Magnetic tape reels in the prior art have generally comprised either a metallic hub with spaced flanges attached thereto, or an all-plastic reel having both a plastic hub and plastic flanges attached thereto.
Prior art metallic hub reels have suffered several disadvantages, the principal one being the high cost of manufacture, both in the material and labor costs. Additionally, the metal hubs have a substantially different coefficient of thermal expansion from that of the tape and may cause stretching of the tape if the tape and reel are exposed to low temperatures.
Such high costs of manufacture have been ovecome to a large extent, by the use of synthetic resins or plastics for both the reel hub and its flanges. However, the prior art plastic reels have suffered numerous problems of their own. The primary problem of plastic reels has related to the inability of the plastic hub to withstand the compressive forces imparted to the hub by the wound tape. The requirement that all such reels have a standard groove provided for a recording lockout ring on one side has required an asymmetric design of the hub structure, with the reel having greater strength against compressive forces on the side opposite that having the lockout ring groove. This asymmetric design has thus resulted in an asymmetric distribution of the strength of the reel and its ability to resist deformation under load. Accordingly, when compressive forces are exerted upon the reel hub by the wound tape, especially at the higher tensions of newer tape drives, the reels have often tended to deform slightly in a "coning" manner. Even slight deformation of this nature causes the tape to tend to wind in a conical manner, bearing against one of the flanges, instead of winding squarely outwardly from the hub. Such conical winding tends to impart great stresses to the flange, frequently causing its fracture from the hub and possibly causing destruction of the tape wound thereupon.
Accordingly, it is an object of this invention to provide a tape reel which resists axially uneven compressive deformation. More particularly, it is an object of this invention to provide a reel having a stiffness or resistance to deformation which is generally equally distributed on opposite sides of a plane normal to the reel axis and passing through axial center of the reel. It is a further object of this invention to provide such a reel which is economical to manufacture. It is yet another object of this invention to provide such a reel in which both the hub and the flanges associated therewith are molded of synthetic resin material.